Improving existing messenger + telegram bot creation

The messenger https://gitlab.com/Monsterovich/protox/ needs to be improved by removing access to dev section and making it more user-friendly.
Mentors will work with tg-bot. Participants will install the messenger. All participants should be centralized in one database, which will be operated from the web-admin panel.
Admin panel functionality:
- Registration form creation (for new Participants)
- Sending messages to new Members (possibly via console toxic https://github.com/Jfreegman/toxic)
- Telegram-bot functionality:
The expected capacity of a bot is 15-20 Mentors, who communicate with Participants via voice messages (the mentor in the tg-bot dictates the voice message, and the voice is redirected to the particular participant)

The project can be divided into three stages: messenger customization, admin panel, and tg-bot.

Long-term improvement opportunities should be taken into consideration.

Waiting for your estimates of the time and cost.
Thank you for your attention.